Add contact photo for missed call notifications

+ ContactPhotoLoader to create the appropriate icon from a ContactInfo
- NameLookupQuery in CallLogNotificationsHelper#getContactInfo
  To show a photo the name is not enough. Full query need to be made to
  retrieve the photoUri.
+ class Assert in util
+ Gradle directory setup for dialer tests
  (Note: this is just for project setup in Android Studio, tests are
  still not runnable in gradle)

Bug:27276108
Change-Id: I0ed2147f2bb60454fe5a5ad6c25fe99727441880